I took it to the dealership over the weekend and took one of the techs for a ride (I had to insist, as the dealership really didn't want to do it). The 12 year old that they had ride with me says that it sounded like a tire issue and not a a bearing. Hopefully he's right but I'm gonna check the diff fluid this weekend.

I have the same type of noise, 09 328xi automatic. It's what a call a grinding / humming noise but it also has a thumping noise only when you let off the gas, most noticeable between 40-60 mph, kind of sounds like a out of round tire noise but goes away as soon as you step on the gas. I took it to the dealer and they "assume" it's low on fluid due to an accident the car was in 30k ago! I just bought the car, first BMW for me so I'm not sure how to proceed. I have known the car since new, i know the damage that was done in the accident and it was fixed 30k ago so its hard to accept this problem is due to the accident. Any ideas for me? If it's just low on fluid where to I go to check it? I'm a do it myself kinda guy and I can turn a wrench so any suggestions would help.

i had my front-right bearing replaced under warranty at 12k miles. It began like a hum that I really thought was tire noise, but over the course of time it got louder and louder (even after rotating tires). Finally, any time I was over 40mph it was ROARING.

Dunno what the OP's hum sounds like, but if it gets any louder with time or is still exactly the same after moving tires around, I vote for a bad bearing.

i had my front-right bearing replaced under warranty at 12k miles. It began like a hum that I really thought was tire noise, but over the course of time it got louder and louder (even after rotating tires). Finally, any time I was over 40mph it was ROARING.

Dunno what the OP's hum sounds like, but if it gets any louder with time or is still exactly the same after moving tires around, I vote for a bad bearing.

Thats what I think it is but the dealer is hanging thier hat on the car was in an accident and it's not thier problem, the accident was 25,000 miles ago but I can't get them to budge, my warranty is up at the nd of January.

my mothers 328 had a humming problem that sounds just like that with pitch increasing as speed increases. ended up being diagnosed as an issue with the front differential unfortunately. gl with finding a solution!

Eppieguy - Call up BMW NA. Complain to their customer rep that the dealer is not honoring warranty and this is not the kind of treatment you expect from a luxury brand like BMW. I've done that many years ago when the dealership refused to fix something under warranty (a long time ago on my E46) and I got a call from the dealership's manager to bring my car in for repairs. They even did a full inspection and fixed everything that can be fixed under warranty plus a complete car detail.

Wow, same issue here...2008 335xi. The pitch increases as the speed of the car increases, but has nothing to do with engine speed. I would think that this means it is something beyond the output shaft of the transmission, meaning transfer case, drive shafts, wheel bearings, axles, or tires. The sound is louder when the car is under load (accelerating or engine breaking) and when it is not under load, it gets quiet. I had new tires installed in August, and I was thinking that could be the cause. I will try rotating the tires around to see if the sound moves with them, but I really am leaning toward something with the transfer case.

A coworker of mine just had new tires mounted on his truck. As soon as he left the shop he said he had symptoms similar to yours...humming noise with higher pitch at higher speeds. He went back to the tire shop and discovered that they mounted one of his directional tires backwards.

Since you just had a tire removed from the rim for a patch, you might want to check to make sure they mounted it the right way.

Here is what I would do as I went through this about 30,000 miles ago thinking the worse that my front differential was toast......but it wasn't.

I ended up changing both front wheel bearings...funny thing is the side I thought was making the noise was actually the opposite side. I originally thought it was the drivers side front bearing as that is where the noise seemed to be coming.

Then I thought it may be the front differential as it is on the drivers side and looked to be leaking. Put in fresh oil, thicker and noise still there.....then panic set in as there were only 2 used front diffs in the country, or spend $2000 on a new one.

Finally, my neighbor got my car up on his lift and we determined the front passenger wheel bearing was making some noise, but that didn't cure the problem........ended up finding the fron KW V1 struts were shot on the drivers side....absolutely toast.

Put new struts on and the Humming noise went away! Must be the struts dampen the noises from the wheels and road...basically with a blown strut I had all the vibrations and noises go from the wheel right up through the steering wheel.

Here is what I would do as I went through this about 30,000 miles ago thinking the worse that my front differential was toast......but it wasn't.

I ended up changing both front wheel bearings...funny thing is the side I thought was making the noise was actually the opposite side. I originally thought it was the drivers side front bearing as that is where the noise seemed to be coming.

Then I thought it may be the front differential as it is on the drivers side and looked to be leaking. Put in fresh oil, thicker and noise still there.....then panic set in as there were only 2 used front diffs in the country, or spend $2000 on a new one.

Finally, my neighbor got my car up on his lift and we determined the front passenger wheel bearing was making some noise, but that didn't cure the problem........ended up finding the fron KW V1 struts were shot on the drivers side....absolutely toast.

Put new struts on and the Humming noise went away! Must be the struts dampen the noises from the wheels and road...basically with a blown strut I had all the vibrations and noises go from the wheel right up through the steering wheel.

I know this is old...but this post is exactly what I'm dealing with right now. I did every single thing you've done except put it on a lift.

I pulled the front drive shaft and think the noise is the output shaft on the front diff as it has some rotational slop. However...the noise started the day I put my used KW V3's on. I will be pissed off like a mother trucker if one of the struts is blown. Arghhhh!